The application generally relates to temporal shaping and polarization state modification of ultrashort optical pulses.
The temporal shaping of ultrafast pulses is a field that has seen considerable growth alongside the development of ultrafast laser pulse sources since the 1980s. A conventional apparatus for ultrafast pulse shaping is a Fourier-domain pulse shaper, which performs a real space Fourier-transform on an input pulse, allowing for modification of the frequency components of the pulse. A variety of modulators can be placed at the Fourier plane of the pulse shaper, including liquid crystal arrays.
A conventional approach to building an optical delay line for frequency-domain pulse shaping is to use diffraction gratings as the dispersive elements and transmissive lenses as the focusing optics. They are then put into the “zero-dispersion” pulse compressor configuration, resulting in a Fourier plane between the two focusing elements where the frequency components of the input pulse are resolved, and then modulated. However, this approach only permits controlling frequency on a pulse-by-pulse basis.
Single layer liquid crystal arrays placed at the Fourier plane have been used to modulate the phase of the frequency components of a pulse, or be used to modulate the amplitude of the pulse. In addition, it is known to place dual layer liquid crystal arrays at the Fourier plane to modulate the phase, amplitude or polarization ellipticity of the pulse.
However, to control the full spectral amplitude, phase and polarization control using a single Fourier-domain pulse shaper requires dividing the input pulse into multiple paths and configuring the pulse shaper such that they address different portions of the spatial light modulator.